WASHINGTON (AP) -- The Trump administration is expected to name John Hannah, a onetime aide to Vice President Dick Cheney, as its next special representative for Syria, two people familiar with the decision said Wednesday.

Hannah, who was Cheney's national security adviser, also worked in the State Department during the Clinton and first Bush administrations. He is likely to be named to the post in the coming weeks, according to the two individuals, who spoke on condition of anonymity because they weren't authorized to publicly discuss the appointment.

Most recently, Hannah has worked as a senior counselor at the Foundation for Defense of Democracies. The Washington-based think tank is close to the Trump administration and advocates hawkish policies on national security, and especially on Iran, whose growing influence in Syria has been a major concern for the United States and Israel.

Hannah's appointment comes as the U.S. and other countries struggle to advance U.N.-led efforts to secure a political solution to Syria's long civil war. The U.N. envoy for Syria, Staffan de Mistura, said Wednesday that the current situation is "as "violent and worrying and dangerous" a moment as he has seen in four years. He pointed to escalating violence that he said was undermining peace prospects and threatening the region's stability.

Until recently, U.S. efforts in Syria were largely focused on fighting the Islamic State group, which is still active in certain pockets of the country but no longer controls vast swaths of territory. The Trump administration has cautioned against letting up until the extremist group is totally defeated. Meanwhile, a small number of State Department officials are also in Syria helping to coordinate humanitarian aid and restore stability to areas liberated from IS.

Hannah's selection was first reported by the newspaper Al-Monitor. Hannah didn't respond to a request for comment.